Overlap of the plasmasphere and ring current: Relation to subauroral ionospheric heating

Abstract

[1] The overlap of the ring current with the outer plasmasphere is thought to play a major role in storm-time related increases in the subauroral ambient topside electron temperature. Instabilities generated within the overlap region, Coulomb collisions of plasmaspheric electrons with the ring current ions, and charge exchange are all thought to work either individually or together to generate a downward heat flux into the ionosphere to produce the increase in temperature. Analysis of IMAGE two-dimensional ring current and plasmasphere density maps together with in situ DMSP ambient electron temperature data shows that the heating generally occurs over a small radial extent within the plasmasphere/ ring current overlap region and may be significantly earthward of the plasmapause. This argues against collisional heat conduction as the source of the heat flux and for an instability-based process. The finding that the heating occurs within well-defined ratios of the cold plasmasphere to hot ring current density strengthens this supposition.

Excitation of EMIC waves detected by the Van Allen Probes on 28 April 2013

“…EMIC waves are preferentially generated in regions where hot anisotropic H + and cold dense ion populations spatially overlap [e.g., Jordanova et al, 2001;Pickett et al, 2010;Zhang et al, 2011]. In the terrestrial magnetosphere, these ion populations can commonly be found where the ring current overlaps the plasmasphere or plasmaspheric plumes [Gurgiolo et al, 2005;Thorne, 2010].…”

CLUSTER and IMAGE: New Ways to Study the Earth’s Plasmasphere

“…A quite sophisticated approach is the use of data quality flags to eliminate the Earth's shadow region, the auroral emission, and the seams between the fields-of-view of the three EUV cameras from the analysis (Galvan et al 2008). Not doing so results in erroneous contributions to the solution in the subsequent image inversion process (Gurgiolo et al 2005).…”

“…Subtraction of the image background largely eliminates the adverse effects of straylight in the EUV instrument and facilitates further image processing (Gurgiolo et al 2005;Gallagher and Adrian 2007;Galvan et al 2008). A quite sophisticated approach is the use of data quality flags to eliminate the Earth's shadow region, the auroral emission, and the seams between the fields-of-view of the three EUV cameras from the analysis (Galvan et al 2008).…”

“…Binning has been used by Darrouzet et al (2006a) to detect plasmaspheric plume tips down to relatively low densities. Gurgiolo et al (2005) use a despeckling algorithm to remove isolated active pixel clusters, which can be regarded as an intelligent form of binning.…”

Auroral and sub-auroral phenomena: an electrostatic picture

“…A range of diverging field strengths exists (Karlsson et al, 1998); very strong fields and the associated drifts might produce stable auroral red arcs as a consequence of the ion and electron heating due to ion-neutral collisions (Hoch and Lemaire, 1974;Foster et al, 1994;Moffett et al, 1998). SAPS and SAID have substantial effects on the plasmasphere and the ring current, and on the overall configuration of the inner magnetosphere (Foster et al, 1994;Ober et al, 1997;De Keyser, 1999;Goldstein et al, 2003Goldstein et al, , 2005Gurgiolo et al, 2005;Foster et al, 2007;Voiculescu and Roth, 2008).…”